Method of and apparatus for cooling electron-discharge tubes



Jan. 17,1928. 1,656,826

,7 M. MORRISON METHOD OF AND APPARATUS FOR COOLING ELECTRON DISCHARGE TUBES Filed Jan- 7, 1924 2 Sheets-Shet 1 ul A 12v VENTIOR Jan. 17,1928.

M. MORRISON METHOD OF AND APPARATUS FOR COOLING ELECTRON DISCHARGE TUBES iled Jan- 1924 2 Sheets-Sheet 2 11v VENTOR WWW Patented Jan. 17, 1928.

UNITED STATES "PATENT OFFICE.

MONTFOBD MORRISON, OI! CHICAGO, ILLINOIS.

Application filed January 7, 1924. Serial No. 684,803.

The present invention relates to systems for cooling the anodes of vacuum tubes of the thermionic type, such as hot cathodeX- ray tubes, hot cathode rcctifiers and the like.

.5 Among the objects of my invention are; first, to provide a more effective means for coolin anodes than used in the prior art; secon ,to provide a means for cooling anodes which is less dangerous to human life than i (hose heretofore used; third, to provide a means for cooling anodes which automatically dissipates the heat of the anode from the operating room fourth, to provide a means for cooling anodes which is more comic pact and practical to operate than those of the prior art; fifth, to provide a meansfor cooling anodes which permits the anodes to be at any electrical potential whatever inde pendent of the electrical potential of the prino ma cooling device.

Fig. 1 represents a cross sectlon of one embodiment of my improved cooling system, and Fig. 2 shows the cooling apparatus conuected to an X-ray system, utilizing a recti- 9 tier preferably such'as disclosed in my Patent 1, 166,541, issued August 28, 1923, and a tube holder and protective device preferably such as disclosed in my application 633,712, filed April 21, 1923.

' In the prior art the most efiective means of cooling anodes has been probably that of operating the anodes at groundpotential and supplying them with clrculatingwater from the citys mains at ground potential.

: This system allows an abundance of cooling medium at a low price and low temperature, to be constantly circulated by the reverse face of the anode and is a very convenient set-up for scientific laboratories and the like 40 where comparatively low potentials are used.

As the potentials of X-ray tubes have been gradually raised, the impracticabllity of this scheme at once made itself apparent, as it involves the construction of very speu cial high voltage generators and very special tube-holders which are expensive and impracticable to operate.

To overcome this, cooling water at ground potential was at once abandoned as a hopee less means and the cooling system was insulatedand suspended in open air, so that the anode of'the X-ray tube might be operated at half. potential above ground, which 1s universal practice and most economical and 58 which allows most economical and satisfactory apparatus. Many set-ups have been proposed to provide means for cooling this insulated system. Large glass jars have been provided and the water circulated to and from the anode by means of an insulated pump. Fans have been used to blow air against these jars and various other schemes employed, all of which proved to be entirely ineffective.

In order to make this blowing of air more efi'ective, instead of using glass jars automobile radiators have been employed and the water circulated to and from the radiator identical with the system used in automobiles, and a fan for causing a blast of air to pass through the radiator exactly identical with the systems used in automobiles. There are many disadvantages to such a system. First of all, it is large and cumbersome, it fills up considerable space in the operatln room; the radiator and connections are a at high potential above ground, making them very dangerous to the operators life. The

sharp points in the corners of the radiator give off violent corona streamers which enerate obnoxious gases, sickening those a out it, and the ozone generated by the corona streamers react upon the radiator. parts causing them to leak, which is not only bothersome but is very dangerous to human life to have water at 150,000 volts dripping the ground. Furthermore, this system does not supply an adequately effective means for cooling, for the radiator can only reduce the temperature of the water a certain percentage and the temperature of the outgoing water grows higher and higher as the incoming water increases the temperature. Furthermore, the air being only circulated about the room the temperature of the room is raised considerably, which also raises the temperature of the cooling water being supplied to the anode. All these go to limit the effectiveness of this system of cooling to a very disadvantageous state of affairs.

In my improved system of cooling I provide an insulated circulating system but one which is enclosed within corona-proof shielding and which is only exposed to the surroundings at one place where it is necessary to make connections to my system roper, and I thereby reduce the danger to uman life and further eliminate the generation of ozone and the accompanying obnoxious gases and their resultant effects.

In this system I provide substantially three circulating systems; one at the voltage of the anode, which circulates to and from the said anode, and a second circulating system at ground potential circulating to and from a cooling means at this otential, and a third circulating system whic is composed of a liquid dielectric circulating between the two aforesaid systems.

In this way my system is composed of a structure which somewhat resembles a chain with the links standing out in air; the first link being the circulatin system of the anode, and the second link being the dielectric circulating system between the high potential and low potential systems, and the third link being the low pot ntial circulating system.

It will be appreciated that'I may so insulate these links and operate them so that the potential between the anode and the ground may be divided into any number of links instead of three, depending upon the potential and engineerin economy and the particular insulation invo ved.

As to the means which I employ at low potential for cooling, depends upon what is available and the degree of eifectiveness re quired b the anode. Preferably I use ordinary hy rant water from the city mains, but in-some applications where still more effective means is required, I supply instead of the city mains a small refrigerating machine such as supplied for individual household use, and which is a small, com act and a most effective means for limiting t etemperature of theanode.

Having described my invention in general terms, reference may now be had to the accompanyin drawings.

Fig. 1, 1 1s a duct which conducts the cool ing water away from the anode of the electron discharge tube to be hereinafter described. This heatedwater is conducted into a breathing chamber 2 and thence through a of the electron discharge tube.

duct 3, to a toroidal'spiral 4, formed of this same duct material and located in the lower art of the tank 5, said spiral4 is surrounded a hollow, concentric, cylindrical barrier 6. F rom the toroidal spiral 4, cooling water is led up by means of a continuation of the same duct 7, tea small gear pump 8, such as is lused 01111 screvvi-macflliines and tlie' like for sup yin t e coo ing uid to wor in process, then%e by duct 9 and 1 0 to the anode The gear pump 8, is driven by a motor 11, by .means of an insulator-coupling 12. This allows the pump 8 to be operated at anode potential and the motor 11 to be operated at ground potential.

In the upper part of tank 5 is located a series of helically formed concentric ducts 13 and l constituting a continuous duct, having an inlet at 15 and an outlet at 16. The inlet 15 may be directly connected to a city water main and the outlet 16 connecttoroidal spiral 4 causes its ed to a waste-pipe, or they may be connected to a small refrigerating plant, such as heretofore referred to, or such other coolin means as is available and at low otentia The tank 5 is partiall filled with oil or other fluid insulating die ectric 17.

In the functioning of the device as'a means for cooling anodes of electron discharge tubes, the operation is as follows:

Water from the city mains is connected to duct 15, duct 16 is connected to a waste pipe. Water is turned on and is caused to ClICLllate through the helical duct systems 13 and 14: thus acting to remove from the oil about these helical duct systems any excess temperature over that of the water itself.

Motor 11 is started and the pump 8 being primed by the hydrostatic pressure of the system, as will be appreciated by those familiar with the art, the water in the high voltage duct system begins to circulate.

A pressure is developed in duct 9, forcin the water through duct 10 to the anode and back through duct 1 into the breathing chamber 2, through the duct 3 and through the toroidal spiral duct circuit 4. and thence to the pump again. The water circulating through the toroidal spiral 4 imparts some of its heat to the surroundin oil, and the directing barrier 6 constrains his heated oil to rise to the surface in the direction of the indicated arrows, 18 and 19.

The removal of this heated oil from about riorly occu ied space to be replaced by ot er oil whic is drawn downward from the upper helical system in the general direction of the curved arrows 20 and 21. This motion in turn draws the aforementioned heated oil which has arisen to the upper region 22 and 23, through the cooling ducts '13 and 14 in the general direction of the curved arrows 24 and 25. Thus the oil in its circulation forms the middle link of the chain heretofore referred to; the high potential circulating water system being one outside link and the low potential circulating system being the other outside link.

It will be appreciated that my invention is not limited to oil in the tank 5, nor is it limited to water circulating'through 1 and 10, throu h 15 and 16. As a matter of fact, an suite le fluids may be used.

t will be ap reciated that the li uid circulating throug 15 and 16 may be rought to' a very low temperature, depending upon the liquid used, an thus the liquid dielectric in the tank 5' may be cooled to almost any extent desired, and therefore the liquid in the high voltage circulating system may work much more effectively than those systems heretofore in use.

Referring to Fig. 2, the several arts of Fig. 1 will be recognized by their 'ke numerals.

III

Further, the duct 1 is continuedup to the anode 26 of an X-ray tube 27 and back again, forming a continuous circulating system at high potential. 38 represents a source of cooling medium.

The duct line represented by 1 and 10, in Fig. 2, and more in detail in certain parts in Fig. 1, is insulated from the duct line represented by and 16, Figs. 1 and 2, and since the duct line represented by 15 and 16 is operated substantially at ground potential, the duct line represented by 1 and 10 is, therefore, insulated from ground and operated at potentials above that ground such that the liquid flowing to and f m the anode is insulated from ground, under operation.

28 is a source of alternating potential which supplies the step-up transformer 29 with energy, the circuit of which may be supplied with a switch 30 for practical purposes. 31 is a high potential rectifier as described in my aforecited patent, 32 is an X-ray tube filament-heating transformer common to the art, which may be supplied with a regulator 33 and a switch 34 for practical purposes. Motor 11 is suppliedby means of leads 35 and a connecting switch 36, with power from source 28. 37 is an X-ray tube holder and protective shield, as fully described in my heretofore cited patent application.

What I claim is:

In an electron discharge apparatus comprising an anode subject to elevation of temperature by electron discharge thereupon and said anode subject to operation at potentials substantially above that of earth, means for circulating a liquid to and from said anode in a hollow insulated duct, means for circulating a second liquid of a lower temperature than that of the aforesaid and at an electrical potential substantiallythat of earth and in a'second hollow duct, the two said ducts immersed in a liquid dielec-' tric providing insulation between said ducts, whereby the heat of the anode is first transferred to the liquid dielectric and thence carried away by; the aforesaid second liquid and duct.

In witness whereof, I have hereunto set my hand this 4th day of January, 1924.

MONTFORD MORRISON. 

